ppc4xx: Move cpu/ppc4xx/vecnum.h into include path

This patch allows the use of 4xx interrupt vector number defines
in board specific code outside cpu/ppc4xx.

Signed-off-by: Matthias Fuchs <matthias.fuchs@esd-electronics.com>
diff --git a/cpu/ppc4xx/4xx_enet.c b/cpu/ppc4xx/4xx_enet.c
index ff707dd..44659ff 100644
--- a/cpu/ppc4xx/4xx_enet.c
+++ b/cpu/ppc4xx/4xx_enet.c
@@ -90,7 +90,7 @@
 #include <405_mal.h>
 #include <miiphy.h>
 #include <malloc.h>
-#include "vecnum.h"
+#include <asm/ppc4xx-intvec.h>
 
 /*
  * Only compile for platform with AMCC EMAC ethernet controller and